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March 26, 1963
' s. BECKWITH
3,082,612
REFRIGERATEIj CABINET AND DEFROSTING MEANS
Filed Feb. 13, 1961
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United States Patent 0 " C6
1
3,082,612
REFRIGERATED CABINET AND DEFROSTING
MEANS
Sterling Beckwith, Libertyville Township, Ill_., assignor, by
mesne assignments, to Dual Jet Refrigeration Company,
a corporation of Illinois
3,082,612
Patented Mar. 26, 1963
2
the bottom and the invention will hereinafter be described
with reference thereto, but it will be understood that the
concepts hereinafter described will also be applicable to
other directions of flow.
It is an object of this invention to provide a method
and means for improving the operational characteristics
as well as the ?owv characteristics of the refrigerated cabié
net and it is a related object to provide a method and
means for the removal of frost separated out upon 8111'‘,
This invention relates to the conditioning of an enclosed 10 faces with which the cold air stream comes in contact
space having an open side for communication of the
and which, if not removed, might interfere with the
enclosed space with the atmosphere and it relates more
desired ?ow characteristics for most efficient operation of
the device.
particularly to maintaining a refrigerated state within the
enclosed space having an open side and which is used for
These and other objects and advantages of this inven
the storage of food products and the like.
15 tion will hereinafter appear and for purposes of illustra
In the copending application of Hagen et al., Ser. No.
tion, but not of limitation, an embodiment of the inven
Filed Feb. 13, 1961, Ser. No. 88,879
9 Claims. (Cl. 62-256)
54,077, ?led September 6', 1960, and entitled “Refrig
tion is shown in the accompanying drawing, in which
erated Display Case,” and in the issued Simons Patent
No. 2,862,369, description is made of a refrigerated dis
play cabinet of the type described. Loss of heat from
the refrigerated storage space through the open side is
refrigerated cabinet embodying the features of this inven
substantially obviated by the use of an air curtain which
is advanced continuously across the open side from one
edge of the opening to the opposite edge in a manner to
FIG. 1 is a schematic sectional elevational view of a
tion, and
,
FIG. 2 is a schematic sectional elevational view similar
to that of FIG. 1 illustrating a further modi?cation in the
cabinet
construction.
_
'
.
Before entering into a discussion of the concepts of
blanket the entire opening.
25 this invention, a brief description will be given of the‘
cabinet and modi?cations thereof.
The air curtain is adapted to be formed of adjacent
panels of air with the inner panel comprising a refrigerated
Referring now to FIG. 1 of the drawing, the condi
cold air panel and one or more outer panels having tem
tioning cabinet is provided in the form of an enclosure
peratures more closely approaching the ambient tempera
having a top wall 12, a back wall 14, a bottom wall 16,
ture from the inside out. For most eiiicient practice, it 30 side walls (not shown) and a front wall IS. The front
wall is provided with an access opening 20 of substantial
has been found to be desirable to recirculate at least the
inner cold air panel and as many of the adjacent guard
dimension for communicating the enclosed space 22 with
panels as possible thereby to conserve on the investment
in the interior of the cabinet with the outside atmosphere.
The cabinet rests upon a suitable base 24.
in the refrigeration required to maintain the otherwise
enclosed space in the desired refrigerated state.
Spaced inwardly from the outer walls of the housing
35
and in substantially parallel relationship therewith are
For example, in the Simons patent, use is made of an
inner walls including a top wall 26, back wall 28, bottom
air curtain formed of but two panels comprising an inner
cold air panel which is refrigerated and continuously
wall 30, front wall 32 and side walls 34, all of which
recirculated and an outer ambient air panel which is cut
de?ne the storage space 22 therebetween. The space
off from the cold air panel at the opposite side of the 40 between the inner Walls and the outer Walls of the cabinet
access opening for return to the atmosphere. In the
is subdivided in FIG. 1 by a partitioning wall 36'to de?ne
two separated passages 38 and 40- which extend substan
aforementioned copending application of Hagen et al.,
illustration is made of a modi?ed arrangement which
makes use of an inner cold air panel and an outer panel
tially continuously about the storage space 22 from the
made of an arrangement wherein the nozzles extend across
the bottom edge of the access opening to direct the air
42 is an air circulating means such as a fan 52 or blower
which operates to induce the ?ow of a stream of air
inlet openings 42 and 44 across one edge of the opening
both of which are recirculated through separate systems 45 2th to outlet openings 46 and 48 across the opposite edge
of the opening.
in the cabinet whereby the outer panel acquires a tem
The passage 38 is provided with refrigeration coils 50
perature intermediate the cold air panel and ambient
through which a suitable refrigerant is circulated for
temperature to function as a guard panel which mini
passage in indirect heat exchange relationship with the
mizes heat loss while, at the same time, enhancing laminar
?oW of the air panels making up the air curtain. Also 50 air traveling through the passage 38 for the refrigeration
thereof. While refrigeration means 50‘ is illustrated as
disclosed in the aforementioned copending application of
being located in the bottom run, adjacent the inlet to the
Hagen et al. is an arrangement wherein the curtain is
formed of three recirculating panels in side-by-side rela
passage, it will be understood that the refrigeration means
may be disposed in other parts of the passage but prefer~v
tionship thereby further to increase the efficiency of
operation from the standpoint of laminar ?ow charac 55 ably in the direction towards the ‘inlet.
Located in advance of the refrigeration means 50 and
teristics and heat loss from the conditioned space.
preferably between the refrigeration means and the inlet
In the aforementioned constructions, description is
panels upwardly across the opening towards inlets simi
through the passage 38 from the inlet 42 to the outlet 46
larly extending across the top side of the access opening. 60 and, in accordance with the concepts of this invention,
Description is also made of an arrangement wherein the
from the outlet 46 across the access opening 20 to the
nozzles are located across the upper edge of the opening
inlet 42 for recirculation of the cold air stream.
for projecting the air panels downwardly across the open
Similarly located Within the outer passage 40 is another
ing to inlets arranged across the bottom side of the 65 air circulating means 54, such as a fan or blower, for in
ducing the ?ow of air through the passage 40* from the
opening. It will be understood that the air nozzles can
inlet 44 to the outlet 48 and then, in accordance with the
also be located across one of the lateral edges of the
concepts of this invention, from the outlet 48 across the
opening for directing the corresponding air panels across
access opening to the inlet 44 for recirculation of they
the opening towards inlets in the opposite edge. Because
guard jet.
of the more desirable effect of gravity on the higher 70
The outlets 46 and 48 are provided with nozzle mem
density cold air, it is preferred to ?ow the air curtain
bers 56 and 58 adapted directionally to channel the air
downwardly from nozzles across the top to inlets across
streams issued therefrom for laminar flow across the‘
3,082,612
4:
open space from the outlets to the inlets as previously
described. For this purpose, it is desirable to make use
of nozzles of a vane construction, such as a honeycomb
section; preferably. having an effective length greater
than about 1 inch and up to about 5 or 6 inches. The
streams of air issuing from the outlets 46 and 48 form
continuous inner and outer air panels 60 and 62 which ex
tend across the access opening Zilfrom the outlets to the
inlets with the inner panel 69 representing the refrigerated
or cold air panel which is adapted to maintain the storage
space in a desired refrigerated state. ‘Both of the inlets
can be provided with screening members 64 to prevent
the entrainment of solid materials, insects and the like
into the passages.
From the foregoing brief description of the basic con 15
struction of the refrigerated cabinet, it will be apparent
that there is provided an inner cold air panel 60‘ and an
outer air panel 62 which will acquire a temperature inter
shut down the refrigeration of the cabinet and it is a fur
ther concept of this invention to effect snow or frost re
moval from the vanes of the cold air nozzle and prefer
ably to achieve such snow or frost removal from the
vanes in combination with the defrost of the refrigerah
ing coils thereby rapidly to recondition the cabinet for
normal operation.
Forthis purpose, the cabinet is formed with one and
preferably a number of laterally spaced apart passages 80
communicating the ambient atmosphere with ports 8-2 in
the walls of the passage 38 beyond the inlet 42 but be
fore the circulating fan 52 and the refrigeration coils 50.
The passage 38 is provided with a shutter plate 84 piv
oted on the outer wall above the ports 82 for rocking
movement between a raised position to span the passage
38 for blocking the movement of air therethrough while
freeing the ports 82 to a lowered position wherein the
passage 38 is free for normal circulation of the cold air
stream therethrou-gh while the ports 82 are blocked. For
this purpose, the shutter plate 84 is dimensioned to have
a length corresponding to the length of the passage and
mediate the temperature of the cold air panel and the
ambient atmosphere. The guard panel 62 operates to
guard the cold air from the heat of the atmosphere and
a width at least as great as the width of the passage or
to minimize the loss of cold air into the atmosphere since
the distance between the pivot and the far end of the
air entrained from the guard panel into the cold air panel
ports 82.
will be at considerably lower temperature than the air
Another similar group of passages 86 communicate the
from the atmosphere which otherwise would be admixed.
ambient atmosphere with ports 88 in the walls of the
Further to minimize heat loss into the cold air recircu
passage 38 beyond the refrigeration coils and preferably
lated through the passage 38, it is desirable, though not
closely adjacent thereto. Another shutter plate 90 is piv
essential, that the partitioning walls 36 and the outer wall
otal'ly mounted on the wall of the passage 38v above the
14 be provided with suitable insulation, as designated by
the numeral 66, and it is also preferred that the passage 30 ports '88 for rocking movement between a raised position
to extend across the passage 38 for blocking the move
38 be separated from the storage space by an inner wall
26, 28 and 30 having relatively good heat conductivity
so that the cold air traveling through the passage 33 will
be effective to refrigerate the space.
.
ment of air therethrough and freeing the ports 88 to a
lowered position for freeing the passage 38 for the flow
of refrigerated air therethrough while blocking the ports
88. For this purpose, the shutter plate 90 is dimensioned
to have a length corresponding to the length of the pas
sage 3-8 and a width at least as great as the width of the
provided whereby the air panels extending across the ac
passage 38 or the distance between the pivot and the far
.cess opening 26 will correspond to the number of such
end of'the ports 88. The gates 84 and' 90; are adapted
jets. In the modi?cation illustrated in FIG. *2, an addi
tional partition 68 is provided in the cabinet to make avail 40 to be operated together whereby the gates are both shifted
to raised position together so that the circulating fan 52
able a third passage 70 which is provided with a fan or
causes ambient air to be drawn into the passage 38‘ from
blower 72 for the recirculation of an outer air stream
the passage ‘80 and to be returned to the atmosphere
through the passage 70 from an inlet 74 to an outlet 76
through the ports 38 and the passage 86 until the warm
and, in accordance with the concepts of this invention,
ambient air has been effective to achieve defrosting of the
from the outlet 76 across the open space to the inlet 74.
refrigeration coils 50, either by melting or by evaporation.
Thus the air curtain is formed with a third air panel 78
which is located outwardly adjacent the panels 60 and 62, . The passage 38 is provided with a drain 9-2 for venting
By way of still further modi?cation, instead of making
2 use of a single guard jet, additional guard jets may be
For best practice in maintaining desirable laminar ?ow
characteristics between the panels, it is desirable to pro
. the water that is produced upon defrosting of the coils.
Upon removal of the frost from the surfaces of the
vide for air velocities within the range of about 50 to ' 50 refrigeration coils 50‘, the shutter plates v84 and 90‘ can
1,000 feet per minute and preferably Within the range of
100 to 400 feet per minute.
’
‘
be returned together to normal, lowered position where
by the cold air panel is reformed for recirculation from
the nozzles 46 across the access opening 20 to the inlets
Because of the marked reduction that takes place in
the temperature of the air as it shifts gradually from the
42 to the passage 38 through which it is ‘again recirculated
ambient atmosphere into the outer air panel and from the 55 past the defrosted refrigeration coils.
outer air panel’ to the guard panel and from the guard
For rapid defrost, it is desirable to’ shut off the circula
panel to the cold air panel, it will be apparent that the
tion of refrigerant to the evaporator coils 50‘. It is
relative humidity of the air will be increased with corre
preferred, however, to shiftthe cold air channel from
sponding reduction in temperature to the extent that the
the inner panel to the adjacent panel during the defrost
air making up the guard jet and most likely the cold air 60 cycle thereby to minimize’ the amount of temperature
panel will reach a state of complete saturation whereby
rise that is permitted to take place in the refrigerated
frost formation will occur. Such a frost will usually sep
space. However, it is desirable to achieve this objective
arate out onto surfaces engaged by the air stream and
without interference with the defrost cycle and without
more preferably the cold surfaces,‘ such as the evaporator
delay in the return of the elements to normal operation.
For this purpose, the guard passage 40 is provided with
Such portions of frost or excess moisture as are not
plates.
'
"
7
removed ‘by the refrigeration coils will usually subse
quently separate out on surfaces’ encountered by the mov
an auxiliary refrigerating coil $4 through which the re
7 frigerant is bypassed when shut off from the main re
frigerating coils 59 in the passage 38 during thedefrost
ing stream of cold air, the most likely surface being the
ingoing side of the vaned or honeycombw sections ‘forming 70 cycle. Thus the guard ‘panel is able temporarily to func
tion as the cold air panel without'stopping operation of
the nozzles from which the airstreams are projected
across the access opening of the container.
‘ 7
~ the device. Any frost collected on the evaporator coils in
'the guard passage 40' will eventually be removed when
It is an important concept. of this; invention to provide
asimple and e?'icient'means for rapid defrosting of the 7 the guard passage is returned to normal operation for the
refrigerating coils without the. necessity completely to 75 recirculation of air therethrough since the air in the
5
guard panel is usually at a temperature below ambient
but above freezing temperature.
The period of defrost of the refrigeration means in the
cold air passage affords an opportunity for removal of
snow or frost separated or otherwise collected on the vanes
6
across the opposite side of the access opening, inner and
outer passages communicating ‘with the inlet members and
the inner and outer outlet nozzles respectively, means for
causing streams of air to ?ow through said passages from
the inlets to the outlet nozzles and from the outlet noz
zles as air panels making up an air curtain ?owing con
tinuously across the access opening to the inlet members
of the cold air nozzle 56 and particularly on the ingoing
side. For this purpose, the shutter plate 98 is constructed
to permit the passage of a slight flow of air beyond the
for recirculation through the passages, refrigeration means
plate for continued flow through the passage 38 to the
nozzles on the out-going side thereof. Immediately in 10 in the inner passage for refrigeration of the stream of air
?owing'therethrough whereby the inner air panel of the
advance of the nozzles the passage is provided with a
air curtain comprises a cold air panel, ports within said
, heating element 95 of relatively small capacity, such as
inner passage before and beyond said refrigeration means,
small resistance wires or heaters which ‘are su?’icient to
means communicating said ports with the ambient atmos
raise the temperature of the small amount of air which
is permitted by the raised plate to continue to flow 15 phere, and means shiftable in said inner passage and as
sociated with each of said ports for movement between
through the passage 38 but which would be relatively in
unblocking position to blocln said ports and free said
effective when confronted by the large volume of cold
passages to permit normal ?ow of the cold air stream
air normally circulated through the passage when the
continuously through said inner passage and blocking
shutter plate is lowered. Thus the heat is taken up by
.position for blocking said passage and freeing said ports
the slight ?ow of air for carriage of heat to the vanes
for communication with the ‘ambient atmosphere for ?ow
where the heat is eifective to melt the snow or frost and
of ambient air into said passage, through said refrigeration
provide for substantially complete removal thereof.
means, and then out of said passage for defrosting the
It will be understood that the shutter plate construction
refrigeration means.
for blocking and unblocking the passages can be of other
2. A refrigerated cabinet as claimed in claim 1 in which
conventional constructions, such as slide gates or drawers 25
the ports comprise one port located between the refrigera
or combinations thereof. It will be further understood
tion means and the inlet member and another port located
that the guard passage 40 need not be provided with
between the refrigeration means and the outlet nozzle.
auxiliary refrigeration means, especially when one or
3. A refrigerated cabinet as claimed in claim 2 in which
more other guard jets are employed in combination there
with since the defrost cycle can be reduced to a matter 30 the means for causing a stream of air to flow through the
passage comprises a fan means located between the re
of a few minutes, especially when heaters are employed in
frigeration means and the port beyond the inlet member.
advance of the fan 52 to increase the temperature of the
4. A refrigerated cabinet as claimed in claim 1 which
ambient air used to defrost and/or when the refrigera
includes drainage means communicating with said re
tion cycle is modi?ed to circulate exhaust from the com
pressor through the refrigeration coils for more rapid 35 frigeration means for the removal of moisture upon melt—
defrost both internally by the exhaust and externally by
ing the frost.
the ambient air.
5. A refrigerated cabinet as claimed in claim 1 in which
the outlet nozzles are arranged in adjacent side-by-side
When a system is adopted to make use of the hot ex
haust gases from the compressor of the refrigeration sys
parallel relation.
tem for circulation of the hot gases through the evapora 40
6. A refrigerated cabinet'as claimed in claim 5 in which
tor coils St} to accelerate defrost, the concept heretofore
the outlet nozzles are arranged in side-by-side relation
described of using a heating element in advance of the
across the top of the access openingand the inlet mem
cold air nozzle for preheating the small amount of air
bers are arranged in side-by-side relation across the bot
tom of the access opening.
allowed to circulate past the shutter plate can be elimi
nated. Instead, the residual heat in the coils, immedi 45 7. A refrigerated cabinet as claimed in claim 1 in which
ately following defrost, will be su?icient to introduce
the means shiftable ‘between blocking and unblocking
enough heat in the initial portions of the air stream con
position comprises a gate pivoted on the wall of the inner
tinued to be passed therethrough to effect the desired de
passage and dimensioned to have ‘a length at least as great
frost of the nozzle vanes after the shutter $0 is returned
as the distance from the pivot to the farthest end of the
to normal position.
50 port.
It will be understood that the outlet nozzles may be
8. A refrigerated cabinet as claimed in claim 1 which
positioned to extend across any of the sides of the open
includes a second refrigerating means in the adjacent pas
ings with the inlet members being positioned to extend
sage.
across the opposite side for the passage of the air current
9. A refrigerated cabinet as claimed in claim ‘8 which
crosswise therebetween.
55 includes means for supplying refrigerant to said refrigerat
It will also be understood that various changes may be
ing means in the cold air passage and means for shutting
made in the details of construction, arrangement and
off refrigerant from said refrigeration means in the cold
operation without departing from the spirit of the inven—
‘air passage and by-passing thev refrigerant to the refrigera
tion, especially as de?ned in the following claims.
tion means in the adjacent passage at about the same time
I claim:
6 0 that the vblocking ‘and unblocking means is shifted to
1. In a refrigerated cabinet having an enclosed storage
‘blocking position and vice versa.
space with an access opening in one wall communicating
the interior of the storage space with the ambient atmos
phere, adjacent inner and outer outlet nozzles extending
continuously across one side of the access opening and
corresponding inlet members extending continuously
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,466,876
2,33 6,039
Brouse ____________ __-___ Apr. '12, 1949
Weber ___ ____________ __ May 27, 1958